All US visa applicants will now have to undergo social media screening.
The US State Department regulations said applicants will have to submit social media names and five years' worth of email addresses and phone numbers.
"National security is our top priority when adjudicating visa applications, and every prospective traveller and immigrant to the United States undergoes extensive security screening," it said in a statement.
"We are constantly working to find mechanisms to improve our screening processes to protect US citizens while supporting legitimate travel to the United States."
Certain diplomatic and official visa applicants will be excluded from the screening.
First proposed in March 2018, it's expected to affect about 15 million visitors.
Previously, it was applicable only to those applicants who needed additional vetting.

Peace deal hopes fade after Trump rejects 'garbage' Iran proposal
Brazilian flotilla activist returns home, alleges torture during Israel detention
India's Modi to begin five-nation tour, including UAE
UK's Starmer under renewed pressure as lawmakers urge him to quit
Malaysia searches for 14 missing after migrant boat capsizes
Trump says Iran ceasefire 'on life support' after he rejects Tehran's response
Hospitals evacuated, MSF services halted as rival gangs clash in Haiti's capital
EU ministers agree on sanctions targeting violent West Bank settlers
